This invention relates generally to practice balls for use in practicing golf strokes with balls and more particularly to an improved practice golf ball which, when stroked, flies through a short flight distance yet with a flight characteristic such as to indicate any error made by the practicing golfer.
For practicing golf strokes by actually hitting golf ball, golf practice ranges are ordinarily utilized. Alternatively, where an empty space of an area sufficient for free swinging of golf clubs is available, a net enclosure with only one open side is erected in that space and used for practice.
The latter method is convenient and inexpensive but can be utilized merely for swinging a golf club and striking a ball, and the character of the shot or the flight of the ball cannot be determined. For this reason, the practicing golfer goes through his practice without knowing whether or not he has made each shot correctly.
In contrast, a golfer practicing at an ideal golf practice range can see the character of each of his shots and therefore can carry out correct practice. However, in many golf practice ranges, particularly in urban areas, the distance from the teeing ground to the back net is shorter than (as short as 1/3 of) the maximum possible driver shot distance. Consequently, the actual distances hit cannot be determined and, moreover, slices and hooks, which become discernable only beyond this short distance, and their degrees of curvature cannot be observed. In such short ranges, therefore, the golfer cannot carry out fully effective practice. Accordingly, a golf practice range of great scale becomes necessary for effective practice, but such a golf practice range requires an enormous land area and a great expenditure. Actually, such a large practice range is impractical within most large cities or even suburbs thereof.
A solution to this problem could be achieved if the flight characteristics of a golf ball stroked in the regular manner could be indicated or determined in a short distance. For this purpose, a regular golf ball cannot be used, but the use of a ball of light weight and larger air resistance appears to be one possible solution. While known practice golf balls have been developed with this object in view, their greater object of making the energy of the ball in flight very small has been to prevent causing damage to surrounding objects and injury to nearby human beings and animals even when these balls are used for practice in small spaces. For example, a hollow spherical structure A made of a material such as felt and having a large number of holes 1 as shown in FIG. 1 is known. The flight distance of a ball of this kind, of course, cannot be compared with that of a regular golf ball hit with the same stroke, and, moreover, the direction of flight of a ball of this kind is unpredictable. When this ball is hit, the feel at impact is poor, and there is no sensation of solid impact, the only favorable feature of the ball being its safety.
Another example of a known practice ball as disclosed in Japanese Utility Model Publication No. 18022/1968 (Utility Model No. 864,925), entitled "Ball for ball-hitting practice", is illustrated in FIGS. 2, 3, and 4. This practice ball B comprises a plurality of ring-shaped sheets made of a synthetic resin which have been folded along diametric folding lines to form elements of Vee-shaped cross section with acute dihedral angle, and which have been so assembled and bonded together that their fold lines are brought together at a centerline. The resulting structure has a spherical shape. By suitably selecting the material of this practice ball, a ball which imparts a much better feel at impact than the ball illustrated in FIG. 1 and produces ample sensation of solid impact can be obtained. The flight distance, however, is excessively short, and, moreover, the line of flight is not stable.